SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9b78340a4520982d00030ef2baed1ffaf894f2a5c8aa04f606fef3d9670c82a' 
  AND token = 'du4qC+p5lk1ouv7YrU9b97dw+GPAbOSXIhZuY6P1XFY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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