SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '24a3aebe9362c036015208e48f5889056f991d16a3ee71c54e81b866cb940dbf' 
  AND token = '75b3Lpgkrd2h62uQmRiEFTwfUV1HryWFh36lnFN2Yso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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