SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '836ec9e03de12c2fd1861d4a2793b755d8b5b4cb155e3d2c74afb873f3447525' 
  AND token = 'L9JDsPY2VhemhvaQb9LS0KxeS/OjVtZCAj6Md9DLPPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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