SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d82869c4082d7431947816ffa38c91886b372748856b38f8999a03d52966279' 
  AND token = 'FY5TeW+eBHTbkOcvMSus4iZPRzs/u34vV98wWwXSh7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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