SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6e51cba0c0bb5152b97aac325e267f3f546ab4512daa634c71a153575ecfcbd1' 
  AND token = 'Jo+b23yWfvQiTAhyTKNg43sKVL+uoqrdBdakUmvvd7M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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