SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f7370782b4cba825404f104b203de36b40ad3b5f0709aafdec14127bcda6644' 
  AND token = 'W2EdrzlWBbUVqlbiM6PrjzBa1cAPLPeEWR+oicbCIZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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