SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7290c9149f69482df08d2d406c02a184ac191d953945f026b5d11d33c117bbfc' 
  AND token = 'pY+TIrhgeTUrBIuDyEVTbsfAugpnMjTdxfhRrAvDGis=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}