SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d87f5774c116c502650ad038d5d2f5625450be60269be205524fb2db939d1df' 
  AND token = 'k+6IhBmVgYFrmyb50NFW5oZbK+TKFFGwN9oqNwwyk9c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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