SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c54672ff4575254239c61120ca923c2fc78f0fc3e6eb992512d101a1de4124ea' 
  AND token = 'tJMbSFo1vvog38+qZtJVv6hKDH9UPPRerYEPqQRU2xw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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