SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f378e075d37872acb98d32d08f2f6beb8944a954dd0f13f2fee2d13e2a1919f6' 
  AND token = '6USsB6TLE5uIjoCs/XOSc7jSW4Aw5r+Kgv1uwNYcIZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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