SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f710e4a8a253811b5ceb4c352181ceb97ff6c56c4a3b1f997baf4984945241f0' 
  AND token = '5MAnBsEgh1kMAwPGZJ89li+SHLO4phSAx7LFoul7VKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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