SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ebb978ecff178783572c96d35a74e7e5a045163ed1d2f8f63db95c91d98bbed' 
  AND token = 'G89pxJKUqIbd7cznzakXo3LLVWqZFBL+PMwVPkn2hJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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