SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f0503737f4263c8a198a43de92156cab3c2ce5355782a6c156f9a5b1b9f4e69' 
  AND token = 'PQ0QwBY8+LalvT3ZgnhdtmjR0UnayPFwkMtZfVCupoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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