SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dea1981570590b696c1ef94449e636b33480e68dde7a889ac00d841143a0e05b' 
  AND token = 'm/dwaCYOYwWYcneUuKAj75KodwrqYJPY1tuzRrACZq8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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