SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c8f70eebd065ef8320d3152396586e4c4ff035e175e1373cca6d2187254f899' 
  AND token = 'pFEJ5QfzPKcztMIPILtOYeoZfLyWTKRZe3ugIOM3mGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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