SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18b97aa0cf4b033afde98932ccc879963ad8164e228373fa1b0d82743d70bbee' 
  AND token = 'UVwsWjqTX+VPXBmwaTdIUkKzUMPT0C2cUQqU783QOMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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