SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6846527dac2d839302f82c2c4b1d5f154be15434b890bde1e08448c6a07df9c4' 
  AND token = 'mDaRzLqEhMiZqBhWIRqzw3QHyk6kSO5K8k9IiVG2lOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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