SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d16d4b93f25cccf98aef5909329012b6cb39a1a83304dd0863a8e56babdebb9' 
  AND token = 'xyknT5PPpEdKyXgVb0fvUwaoZI7+ZjIPRGOe36QZTAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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