SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fea28ccc5e40b734d11c22b5abe4eab5afcd9648aa4cca3275237a1249177650' 
  AND token = 'UqCiT9S98ZwLjggt6uaomkE6sgDtjkvKxfs98ispxuI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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