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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3a1ed19286c3ea527aefae29ef36aa907d4259199cc0b0a3fdc416aa839da55' 
  AND token = 'Z0Zk92GLiZfAmmHKGXlWvDMP7lfBP3Fd/Y7Gic4kzgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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