SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '1fe9a534043d214f483d9abcd492fa526030618815d17d79556fe4afde1a3b18' 
  AND token = 'WOkux3zM7SMPSSlWmRS5KfJ3scK+mknKrXtOI+bEDHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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