SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7cf3591d242adf96c45cc821ef55adef5caca26293cb31ab0a4c8a4e6785320e' 
  AND token = 'VvFGhqE5+mZQwjFeqh/UFQIYfzp9FxZfVvRcNSpxjpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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