SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6948d545ad608ad36eb1120bd535bf25b7067be3e9e29a0def0157a44c694489' 
  AND token = 'ktqeaAq5rsq7awOWHYL5DsacY/0lj2DfOFYwgMWjP1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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