SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2bc3d4e6b5b399a8f6f36b2f9dc84815b2b4f6d8cfc642cee6542ca971bc71b3' 
  AND token = 'w/6Rjd3ZXz9UjC33tHmAq5bJPhu9eKuhvSgW2q1tp6w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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