SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91c8ee1303afc244234573c99024313af285ba52ab674d38c6466fca0dfd7766' 
  AND token = 'vzBGbCWtt93jJDiYMrVIb2gSOnqXLJO9vMypq75umoo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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