SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6013f05a4ada49d01114bb2138150c7558944dbb2ee823fba07f63510f4eccfb' 
  AND token = '81puse4KRxwczbYFy0ofT6xBJl6+aCJYOTsdgzUs4OY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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