SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c51da3a5854a7305ab4888203252cb1da95e51493851cbb877f13922b96121b3' 
  AND token = 'hGJ+ySbTEyjCcR+gb70oJy39SfRpBRZqJV98dj4EA1g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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