SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ada26efe7908523cdf9d3243413e374ea55c8581f83c0171805d3dff66f8e9c' 
  AND token = 'DjMGgNqJsrB+rS4lQYm5QJzBU72Y/I6Sz7Sod0HR2Wo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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