SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50c5ea8213d740662b12946aad3f03f584169409b5648e096327104f4c348867' 
  AND token = 'VhMyEOijYBrvATogoUvuCocgSHRYmv2qhgiFN04XmCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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