SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc3a3df496de1958024746abbebbb269c23871defa1af0e093f421ed873f03da' 
  AND token = 'iwqP/ccFW5NidW17NUZmkvmAqiGSzA7Z+gQx4xERMW4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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