SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cdab450960a1ce96ff701c096d901a4c4ef7ca1443ae899b3f2264376433e09' 
  AND token = 'vwNb9qjad/jS1otRn4d9Yay74egqZ937sMbjrAUILHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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