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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15142a8a9dbd396e3f46164b3624f84a273ece1732b17e1c4396c3bf4fad65c5' 
  AND token = 'IoSzWsK3s+f7k3aknpuwA9vPdbNfKUlEwGq4du/kOsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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