SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f031af21ce5070d21a7641c4b850b1f52e6e4000c68d9e9aa3c4a6780d0976a4' 
  AND token = 'EtlXhIsAxTuMDNxVQFSmlN8FcN41NJYtyE0aKubV5gg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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