SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a73991c71d5f2012bd04599fc61fe4996334f87eef3c6378643080f9031fab9d' 
  AND token = 'lSR0hxKNef9UEVSepQTjogaS/MBfHYit/lYoQ92wljk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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