SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f393cc604378fa2cf55c93f08c4a80c5b93b7186c460e1f8a254136634269f2a' 
  AND token = 'NmzIwpHNYiK4j5SCEyrbPXGZp1/FDB6LGwnXhFXMKjk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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