SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f4f057be8d768fa56eba33a499638b179626a1ba858f4d230ce3a9e293e5aed' 
  AND token = 'BpSnachP6uFAJ9F/wUELl/7bnj57OMVzOyUWPHvviqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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