SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff5994e91952350300c5fbdcf72a59ccda723c88d09340d7122e21d169a29fb2' 
  AND token = 'E7puiWM4i9yR/HSBugaPjfdy4qA2GAvRDOZbmhz/3T8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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