SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cc772ccb34cc9683edba793d84daa08442635eb7ac7606c0a673064a3bc00cd' 
  AND token = '9g9LhU+JRKudcIDBsnA0yYNJRBVoPhaJRdg+jNtYRAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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