SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da5506254e681bfefdb7cb951d52db5058e4c1a91e0b4076d7ce71d10dc6b90b' 
  AND token = 'MjJa0BLKZMZt/ezyjVFA4+cwoApSlUsCxYYd2iKKetA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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