SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '765169f90e929a86c126d479293f861b17c9fe23f41cc7589728f588a138b42d' 
  AND token = '7mn/CWJelAvcWj8zMhmCXHACq/GlzCFe53zG5B54Tkc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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