SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'aa947b02a88a131174beecbd239d24e88d7cfcb5cbccc15e007a9e967e555dfa' 
  AND token = '/4nlaQHu+Z+U9ZwnwvC/2fLPnCOS/gwVAPiV8seNp/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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