SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89f76c80a3965b80c482922535773cbabdf2e04c8c2f75dc2ec8b925b5b4ebf7' 
  AND token = 'j7WCvBp6KEkqRv249NwfqDczCGVbNoynSx+hHHmlkjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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