SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba1308c6c516772f53fcc266736a31284dfad7c85539991a9a462011b9acf5a4' 
  AND token = 'RrSPnVctreih7KVeKENOndiLhkD+wqi7GPMLf1I2cj8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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