SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb855cae03321e5daada18b434149ddf66e0ff0cc587983efa7e5fa5d536b6a0' 
  AND token = 'G0Aan+dRccufrI47urqzFjjJMclS1cWCnjiWNr37uqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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