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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2e3dcfeb734a2c94478a3b2e6fe5f571bd3a1903d18aab82f564d14a9e4e175' 
  AND token = 'U1kQRyNJ+aeW/e3N8DRa+elLfEF9tAgcnF2pHRzQo2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}