SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0575c0224d0d2d712afd16330ca959ff109aac4c5da547d4da9fd30947ba21e' 
  AND token = '/ATcjxWGjuMyRxiDVHqoZfnOiUkDY6GhQZ5IbW5rJWE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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