SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4917bde90a8faf364833f55c90038bb345803bf73fdbda800a64f4575ea85f6' 
  AND token = 'BU8zXk1R+VxlPpUbhDFU4Yc13e7eUISjiHlEWxVcolI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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