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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b6d3bff8c75be8347b8ba0ab2ffa2eb539e4ab0b8781cd82ea75e7a9ea6a835' 
  AND token = 'WUSl03TLVIt9QOWmp00uT057xT/T0TUcbAe2YzAVbys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}