SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a65a52f3847c3238ba43315201fb650e5a594a8e919079ad5c5e7e00b96c03c' 
  AND token = 'gHQhuhfFfyXcU7pLbzxwJnCwa3Sb/1RWKhzYvFjwjn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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