SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '3e7e147781e639d63ae3a877632acdad5e27737947853b34ad27e10efbbf7d21' 
  AND token = '/6FYK+U4aJSAsQXrOvFDepxObxA9lUihJDrYDFdbBgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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