SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e8ef41bfa3e498568a462dbf501ff638d457fccb1530577205ef7df52b98b9c' 
  AND token = 'z0RulIEZ+FTiwuUpEgc5smd6FuAF0KpnEtsouUWIyCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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