SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5c04ab4ffc9a075641658e7d8279aac790ffe64208a6593c7e3a6eaa989c44d' 
  AND token = 'x7qevA7RWrzexf5QjHRXe02kgr2dPas3TzbBRJrpAiA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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