SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c3b5c320a35be235a746e5128aa24b1987df600c0ead6af6bdc76f2fb33ff17' 
  AND token = 'EMDm8KoLzlu7IKHFY6WGq3YWJFURPaRILS+JG5BIXiE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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