SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8797875803da74097af765a74cc42feca7f82b446e31477ec8192fc2000abf47' 
  AND token = 'DsMFKtLSq9DpjC5OFufIHPHFCcB2JoFrtzEE5/48boc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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