SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a984cb35bc57f7ee3e7476939b06c208950e30700615a0a9e8baadec79d10df8' 
  AND token = 'GiARzr+lgtqVjWxSb8ClCY6AYGt8lDIStCqLhE07VH4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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