SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '261757a6ec5954fe4a730e8dabf9b2c5cb292081fc434fe4e4193413a769e51d' 
  AND token = 'gmn4QmeDYZxxOUMTIefm7ZnPD993bdqDowwIVZ+lzeE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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