SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '856141e252ec628ab7a8a49c042cc9f0315f5b035149e5b5ba6f46e8fa5b7cce' 
  AND token = 'ouoeivL71IPoVtk4UJrdJR8RyZ+8KjmGqk84AOtofrE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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