SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '877adeb4511f8137c5809123c5f8c7e4a143bcd01eeb63ff2190602bed09e456' 
  AND token = 'rFXKcOKnBQ6N70pf8+mas+j8VsK1/RghdDljH0PMTj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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