SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a44e5054d713548ee6f6a4a808665f18039ecc21d6771125db1455df58f6e351' 
  AND token = '9EZs0HLmOwEzq0faP1K/WFjInZIf5yUcBovjgpvd70M=' 
  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"
    }
  }
}