SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b511223619ebf127ffa60980774df4d54efa004da6d0f225b6dcc29e6db75256' 
  AND token = 'fNcBV0mi0fqoSKZW3X5S2kT7Z9UDyACV0hHsBqf9Wyo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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