SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fa795d8cd8055a2630a37e726fd8bc1d336b3f38c74f533faf8643b0210b8be' 
  AND token = 'gPIL8sJmpjVz22I8F5JDWXbRE91fyNBFjJSF8i+Y1rY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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