SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e8b84dbb7b4bdff494835feb69a77601a39672ae2cb2d7259c98f6231871abe' 
  AND token = 'UU0kXiOGeNdMK5t5XRHcQcBFq7SkdacYd8K1Wi7uMfs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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