SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '51637e1fecb9112823162d0a581ca28a9b0f17191cc10632e9accaf360bb0bcb' 
  AND token = 'fB8C/TtCk6v057MeUmYEa6QGv5OccEMwwzueVh5xfcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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