SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'f0c5b45b545fbebc010b1f37320256ab880291d983cc7dd6b707c18edbaa3251' 
  AND token = '9xgYU6kQGyULXgg9ZKCwjZn6jEKbD8pOT7iUqTF63Sg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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