SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a88d77087ec1ae4fa7d75648cbdafa00c86cc954fff03d60a814209966c60857' 
  AND token = 'N7QbGiT6nd0xpHgmiz/Nd8DtCnHLum3XnDVglpzT7xE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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