SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c99bb3ab3d13423a800aa515449b98c771aeb20fe3ee3ccdc0280d856dc4137' 
  AND token = 'hKtFTyTo44XlAYawjeLivaCtLa2gq/ByudC1PTrWKcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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