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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52b9b64b3d5f3e9e0b98d4c29c94dbe98532cbdc3c529dda891dc9fa3a9f929c' 
  AND token = 'BVejFVqR0Xcnqi2wVZasTZ1nj5hjN3/9lBPeiQvl1qA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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