SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f670ced17a6acbd5399cce775d2586fec5a0b008726101252f0478646e977321' 
  AND token = 'HMhcZ4qdm6h51Pl0tMXL0dvNEFyPUiZot8mhqEB8Szs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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