SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc5107b8f31ae65db9c1a3e14f91beaeaa300f1a6502542f2ea9fdba9b9b4642' 
  AND token = '93Zuh0CrB/xFx3Ibv40kFjPZn6YgKzj5yYna5CTo7W0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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