SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9842def7e39df2f73484cde39ae1f7040eaf9a2f7caecdc6d81f6fac360d632d' 
  AND token = 'FN2l/aUpBzx+bHlzGOQbzHQCsVMRfX9rimbGXCjImio=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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