SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c7744f9e4e8617c6310dc47468e21335a861dac3e42672c15770596504347ac' 
  AND token = 'CkfXdTaopN/PO+DAduE9bl1GuYnuZFw2gDn7kwLaENI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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