SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '247a48967caa06602bc0a3b5491dfd8788217b7d2776f6f38d77987508e03ece' 
  AND token = '//u6i9ukIVhxYwpz81kRwE0KMo2uZMCecoVvUueH6ZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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