SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '254972208f0cd4d42f17110e55367cf109a14972a27e747f9e4284267eaa3b36' 
  AND token = 'EUeH93dhfuQlE/lcKV/vWj61xxFMMvvgCcU64CNqxYc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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