SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df974a142f729b570a599e86c492fc08c5458f2a1c31fbff7910383ae285380a' 
  AND token = 'h9wak7PParIw/JPIw87pXUL0ko5bu4XobpPxpk9hd5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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