SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38860f584475854af97215a9cfd57cce75bb2816f3a690629dd837a84a7ad72b' 
  AND token = 'aM4Ew/ihXF23rCgy4HkjW5/ZXoOV9ctE8r9yendHk6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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