SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '281ce1c39267eb652254b905e18ebb5d5883587013be68eb698a78dfa5dbe4d8' 
  AND token = 'aBj0nDxQq4mzETeR7hZ/vF8hqWAg3rn7CuqhC8XepEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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