SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '412c9fee1a90b08972e15fc61890b78d49662874edef392c44425132db4ca078' 
  AND token = 'dNv3HvYW2fEbpMnWrvAU25hCb9GovsJrER9mS6mkLWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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