SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a713f6d8cbf0ff5a1714690292456445386d7840d9435175540f304320844708' 
  AND token = 'sSSmVZRpDE0QucIreeCRPTswFN6BPK/FsRzsJJpn+fM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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