SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7dc32d66380074891a237a973b36473286ca8085bee2e3fe242e8679df390ea3' 
  AND token = 'rmNFAQVGy6iwWbulAsamk5mfIyXT1ozqAZkcGpTBbj8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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