SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18dbb75238a7be102b81b1d67075245b7210d700f4ca16ed4eba0b2c7f45bf65' 
  AND token = '3KWjIUKMcU8jkuYSZbuJ+Nns8goSwCaUFGQL93hQOdo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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